I will mention few ideas and then clear my point.
First, the big bang theory. All started almost 14 billion years ago with a small singularity (density close to the infinite) that exploded and started expanding (still expanding today). My question: what was before that? According to the scientists accepting the theory this is a silly question since TIME started with the big bang.
Second, the theory of parallel universes, ours is one of them. And there are different flavours and explanations how our universe was created. The one I like is that an accident in one universe created a distortion that lead to the creation of our universe.
When I was a teenager and an avid reader of everything, I came across some theories (as old as old Greek philosophy). And one said that actually nothing exists, everything is actually a huge delusion. As a very simplified comparison… the table I see right now in my dining room does not exist, it is a creation of my mind. As much as I like it, the delusion (about the non-existence of our cosmos) was in the minds of those genius lunatics, the universe exists.
Since your time is limited, I will say only one more example before my conclusion. Monotheist religions claim the Universe was created by God. “Everything” has a beginning, including our universe. But God is outside that “everything” because He is eternal and does not have a beginning. And since I always use my logic (that will not sit well with many, but still, it is my thinking), He Who is outside “everything” is “nothing”, so, (1) God does not exist, or (2) He is something else then described in Holly Books.
Now I have to spell my idea, how was the universe created: NONE OF THE ABOVE, and by the way, none of the theories I read so far has enough credibility for a twisted mind like mine. Reason: there are 2 limits that all theories cannot explain, the infinite and the eternity.
I tackled such ideas in my first SF /Fantasy book The Rise of Esperanto https://www.amazon.com/dp/1525508768/
And for those that enjoy sci-fi, fantasy, dystopian, apocalyptic stories, I suggest my second book, The World Ends Tomorrow,
Thank you for reading,